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Woolly Flying Squirrel

The woolly flying squirrel (Eupetaurus cinereus) is one of the least-known mammals in the world. Eupetaurus is a monotypic genus. It is the largest flying squirrel and the longest sciurid, and in fact it is the heaviest gliding mammal in the world. It is notable for physiological structures and behaviors that are unique to the squirrel family. However, previous to WCS research, virtually all biological data come from nine skins and a lesser number of skulls collected or purchased in the 19th and early part of the 20th century. Until our work, scientists had never observed this species in the wild – information previous to our work consisted of anecdotes or extrapolations based on the skulls and study skins. There had been no confirmed sightings of this species from 1924 until its scientific ‘rediscovery’ in 1994.

Within Pakistan, WCS research suggests the squirrel may be limited to an area only one hundred miles long by fifty miles wide, with a central focus on the district of Diamer in the Northern Areas. Unfortunately, this landscape has been under extremely heavy pressure from human activities. The area has been environmentally degraded by deforestation, hunting, and livestock grazing and browsing. Most wildlife populations have been greatly reduced in number or completely eradicated. Because of the rarity of the woolly flying squirrel and the recent environmental degradation in its center of distribution, this species is considered to be in grave danger of extinction, and it is listed as Endangered by IUCN.

The woolly flying squirrel is currently known to live only in caves and crevices on steep cliffs in the dry conifer forest zone of northern Pakistan. This region was historically well-forested with blue pine (Pinus wallichiana), chilgoza pine (P. gerardiana), junipers, and scattered deodar cedar, spruce and fir in higher and moister side valleys. It is bound in this region to between 2,400 and 3,800 meters in elevation, as below this minimum there is only scattered dry scrub or arid rock desert, and above this maximum is the alpine zone.

The woolly flying squirrel is strictly nocturnal, and dietary analysis suggests that it is highly dependent upon pine needles in its diet. This is an extremely unusual diet but one that may explain the unique hypsodont dental structure, unusual enough that it led to the suggestion that the woolly flying squirrel was not really a squirrel at all.

Research on the woolly flying squirrel is complicated by the fact that two other flying squirrel species overlap with it in parts of Gilgit-Baltistan – the giant red flying squirrel (Petaurista petaurista) and the Kashmir Flying squirrel (Eoglaucomys fimbriatus). All three species are nocturnal and are frequently confused with each other from sign and even observations, despite significant differences in size, color, and other physical characteristics.

The region where the woolly flying squirrel is found was under extreme pressure from illegal logging – called the “timber mafia” by local communities. A number of valleys in the region identified as the core area for the woolly flying squirrel were stripped of trees during the 1990s. The “rediscovery” (by Western science) of the woolly flying squirrel in 1994 and the subsequent determination of the squirrel’s dependence on pine needles for food coupled with the rapid deforestation in this region led to the creation of the WCS Pakistan Program in this core area.

This effort has been ongoing since 1997, and it has led to the protection of forests and wildlife across the region. Estimates based on potential available habitat and local knowledge suggest a woolly flying squirrel population in the core region of Diamer of between 1,000 and 3,000 animals.